The role of humic substances in the mobilization of mercury from watersheds

The Correlations Between Mercury Speciation and Dissolved Organic Matter in the Sediment of the Red Sea

“…The similar slopes between our study and those reported by Grigal (2002) for the THg DOC relationship are likely a function of strong correlation between FTHg and the export of humic material associated with hydrophobic organic matter (Mierle and Ingram, 1991;Grigal, 2002).…”

“…AJES previous studies showed a strong interactions between Hg and DOM have also been indicated by a positive correlation between their concentrations in many natural waters (Andren and Harriss, 1975;Lindberg and Harriss, 1974;Mierle and Ingram, 1991;Meili et al, 1991;Driscoll et al, 1995;Hurley et al, 1995;Watras et al, 1995;Baeyens et al, 1996;Kolka et al, 1999;Shanley et al, 2002).…”

Specific ultra-violet absorbance as an indicator of mercury sources in an Adirondack River basin

“…The strong association of Hg and organic matter in surface waters has long been recognized (Lindberg and Harriss 1974;Mierle and Ingram 1991), and numerous studies of Hg in streams and lakes of mid-and northern latitudes of the northern hemisphere have generally shown strong correlations between dissolved Hg concentrations and dissolved organic carbon (DOC) concentrations, and between particulate Hg concentrations and particulate organic carbon concentrations (POC) (Grigal 2002;Yin and Balogh 2002;Dennis et al 2005;Brigham et al 2009;Riscassi and Scanlon 2011). The association of Hg with organic matter is sufficiently strong in many surface waters, that measures such as DOC or absorbance at 254 nm (UV 254 ) have been suggested as surrogates for Hg concentrations, because Hg analyses are expensive and may be unstable in automated water samplers (Dittman et al 2009).…”

“…Thus, the association of Hg with the aromatic fraction of organic matter may be rooted in the complex chemistry of Hg interactions with natural organic matter. In addition to geochemistry-based reasons why Hg is more strongly associated with aromatic organic matter, this association may also originate through mobilization to surface waters and mixing of Hg and DOM from principal runoff source areas such as humic-rich shallow soils (Dittman et al 2010) as well as riparian wetland soils (Å gren et al 2008;Mierle and Ingram 1991), two locations where preferential storage of Hg has been identified (Grigal 2003). In summary, Hg-DOM chemistry, storage, and hydrology are interrelated in complex ways that are the subject of ongoing research; thus, determining the primacy of any single explanation for an association that is evident at the basin scale may be difficult.…”

Methyl and total mercury found in two man-made Amazonian Reservoirs

“…One of the most important reactions is the formation of extremely strong ionic bonding between mercury and reduced sulphur sites in soil and aquatic organic matter. Strong complexation facilitates the mobility of mercury from natural and contaminated soils and sediments 47 into streams, 48 lakes, 49 and groundwater. 50 This enhanced mobility results in increased water column concentrations of mercury in otherwise pristine lakes and streams.…”